In drilling wells for oil and gas exploration, understanding the structure and properties of the associated geological formation provides information to aid such exploration. Measurements in a wellbore, also referred to as a borehole, are typically performed to attain this understanding. However, the environment in which the drilling tools operate is at significant distances below the surface and measurements to manage operation of such equipment are made at these locations.
Magnetometers are used in ranging applications to measure magnetic fields and magnetic field gradients. Such measurements can be used to detect the presence of nearby well casing, for the purpose of intersecting the well or, in steam assisted gravity drainage (SAGD) applications, to drill a well parallel to an existing well at a specified constant distance. The typical range of detection can be of tens of meters, with the range of detection being crucially dependent on the minimum signal level that the sensors are able to measure. Use of such sensors can include errors in measurement. The errors in such measurements may affect the precision or quality of the information derived from such measurements.